Looks like you are getting there. Would keep the wc going to keep nitrates below 40 and dose to 2~4 ppm ammonia till both ammonia and nitrite go to 0 in 24hrs. for a few days.
Was looking back over the thread for hardness tests and finally found them. If your kh is beween 2 and 4 that is a major contributor to your deminishing ph after water change. If I remember correctly kh needs to be close to or above 5 to have a fairly stable ph. With that low of a kh I would suggest doing ph test just before lights out and just before lights on even with no co2 being added I would suspect you could be having larger than is good ph changes in a 24 hr period. I have read that more than 1 point total ph change in 24 hrs. 7 to 6 back to 7 ph can be stressfull on both fish and some plants. I am not sure so you may want to ask or research first but I think it is baking soda that you can use to raise kh to acceptable and more stable lvls. I do not know and can't find the dosage to use though and since my water is 13~16 kh I have never had to remeber what it is. I know it is said that what ever your ph is at is ok and I beleive this to be true but a constantly changing ph is not good and needs to be stableized. The reason for lights on lights off is it = plants on plants off for highest and lowest c02 content for largest ph differences in 24 hrs.
Being new to all this stuff I am not sure I am correct so you will want to check my thoughts but if what I am thinking is correct the constant ph change with wc and then ph decline could be contributing to your shrimp loses.
good luck hope all turns out well.
Was looking back over the thread for hardness tests and finally found them. If your kh is beween 2 and 4 that is a major contributor to your deminishing ph after water change. If I remember correctly kh needs to be close to or above 5 to have a fairly stable ph. With that low of a kh I would suggest doing ph test just before lights out and just before lights on even with no co2 being added I would suspect you could be having larger than is good ph changes in a 24 hr period. I have read that more than 1 point total ph change in 24 hrs. 7 to 6 back to 7 ph can be stressfull on both fish and some plants. I am not sure so you may want to ask or research first but I think it is baking soda that you can use to raise kh to acceptable and more stable lvls. I do not know and can't find the dosage to use though and since my water is 13~16 kh I have never had to remeber what it is. I know it is said that what ever your ph is at is ok and I beleive this to be true but a constantly changing ph is not good and needs to be stableized. The reason for lights on lights off is it = plants on plants off for highest and lowest c02 content for largest ph differences in 24 hrs.
Being new to all this stuff I am not sure I am correct so you will want to check my thoughts but if what I am thinking is correct the constant ph change with wc and then ph decline could be contributing to your shrimp loses.
good luck hope all turns out well.